2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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6/06/2017  |   11:45 AM - 12:00 PM   |  BETTER ESTIMATES OF STREAM GAS EXCHANGE USING ARGON RATHER THAN SULFUR HEXAFLUORIDE   |  306A

BETTER ESTIMATES OF STREAM GAS EXCHANGE USING ARGON RATHER THAN SULFUR HEXAFLUORIDE

Gas exchange is a parameter needed in stream metabolism and trace gas emissions models. Estimates of oxygen (O2) gas exchange using sulfur hexafluoride (SF6) need to be scaled by their Schmidt number ratio, but this scaling is uncertain under conditions of high gas exchange via bubbles. Because argon (Ar) and O2 have nearly identical Schmidt numbers and we can easily measure Ar using membrane inlet mass spectrometry, using Ar additions to measure gas exchange provides a better estimate of stream gas exchange to inform metabolism models. The mean ratio of gas exchange from Ar and SF6 methods in a hierarchical exponential decay model was 1.84 (credible interval 1.00-2.64) compared to the expected 1.35. We found that SF6 underestimated gas exchange in steep streams with high bubble mediated gas transfer. Additionally, estimates of gas exchange using metabolism estimates from diel O2 concentrations in a hierarchical Bayesian oxygen model produced similar results to the estimates from Ar additions. Because Ar is a better proxy for O2 and is easily measured, we suggest using Ar additions to measure stream gas exchange.

  • S19 Elements and energy as fundamental currencies of nature: using ecological stoichiometry as a tool to advance the sustainability of freshwater ecosystems
  • C01 Algae
  • C10 Biogeochemistry

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Presenters/Authors

Hilary Madinger (), University of Wyoming, hilary.madinger@gmail.com;


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Robert O. Hall (), Flathead Lake Biological Station, University of Montana, bob.hall@flbs.umt.edu;


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